Spinal cord stimulation is used to alleviate chronic pain by stimulating the central nervous system. Typically, a lead having a plurality, but usually four or eight, of electrodes is placed in the epidural space, in close proximity to the spinal cord. The lead is connected to a power source 2, which typically includes a disk-shaped or rectangular casing for housing a battery that is implanted in the patient's buttock 8, as shown in FIGS. 1 and 2. When activated, the power source delivers a pulse of energy to the electrodes, which in turn deliver a precise, mild electrical impulse to the spinal cord or to a peripheral nerve. The electrical impulses activate pain inhibitory mechanisms to block the pain signal from reaching the brain.
However, given that the typical power source is somewhat puck-like, the power source has a somewhat substantial size, including significant thickness. Typical power sources have a length and width or diameter of about 5-6 centimeters and a thickness of approximately 1.4 centimeters. Thus, some patients, including those who do not have much adipose tissue in their buttocks, may find that the power source creates a bulge with defined edges beneath the skin that is clearly visible, even under clothing.
Thus it can be seen that needs exist for an improvement to a power source for energizing implantable medical devices, such as a spinal cord stimulator, that minimizes the appearance of the power source beneath the patient's skin.